Next generation wireless communication systems will use greater peak transmission rates in comparison to existing wireless communication systems. For example, 4G (fourth generation) mobile communication systems require a 1 Gigabit per second (Gbps) transmission rate. However, to the inventors' knowledge the existing mobile communication systems can only support less than 100 Megabits per second (Mbps) peak transmission rate using 5-10 MHz radio bandwidth.
In order to mitigate the inter-symbol interference (ISI) when supporting very high transmission rate, orthogonal frequency division multiplexing (OFDM) based multiple access (e.g. OFDMA, orthogonal frequency division multiple access) is the baseline transmission technology for the next generation wireless communication systems (e.g., WiMAX 2.0 or LTE-Advanced systems) through the frequency selective propagation channels.
In addition, next generation wireless communication systems may also utilize a much wider radio bandwidth (e.g. >40 MHz) for data transmission so as to achieve much higher peak transmission rate than current systems. Multi-carrier technology enables this functionality by transmitting multiple radio signals on top of different RF carriers to utilize multiple frequency channels across a wider radio bandwidth.